The effect of thermal and acid treatment of kaolin on its ability for cyanide removal from aqueous solutions
The effect of thermal and acid treatment of kaolin on its ability for cyanide removal from aqueous solutions
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DOI：
10.1007/s12665-019-8408-8
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发表时间：
2019-07-01
影响因子：
2.8
通讯作者：
Veglio, Francesco
中科院分区：
文献类型：
--
作者：
Behnamfard, Ali;Chegni, Kamran;Veglio, Francesco
研究了高岭土、煅烧高岭土（偏高岭土）和酸处理偏高岭土对水溶液中游离氰化物的去除效果。未经处理的高岭土对氰化物没有吸附能力，但煅烧和酸处理可显著提高其吸附性能。确定了最佳煅烧条件为：煅烧温度600 ℃，煅烧时间1h。采用扫描电镜（SEM）、波长色散X射线（WDX）、X射线荧光（XRF）和X射线衍射（XRD）等分析手段对吸附剂的吸附性能进行了表征。当氰化物初始浓度从25 mg/L增加到531 mg/L时，偏高岭土的负载量从0.66 mg/g增加到5.32 mg/g，酸处理偏高岭土的负载量从1.33 mg/g增加到10.67 mg/g。氰化物在两种吸附剂上的吸附动力学随着初始氰化物浓度（25- 531 mg/L）和溶液温度（30-50 ℃）的增加而增加。两种吸附剂上的平衡和动力学数据最好分别由Freundlich等温线和伪二级动力学模型拟合。热力学研究表明，氰化物在两种吸附剂上的吸附都是自发的吸热过程。测得偏高岭土和酸处理偏高岭土对氰化物的吸附活化能分别为16.68和5.79kJ/mol，表明氰化物在偏高岭土上的吸附是化学吸附，而在酸处理偏高岭土上的吸附是物理化学过程。
The removal of free cyanide from aqueous solutions was investigated by kaolin, calcined kaolin (metakaolin), and acid-treated metakaolin. The kaolin in raw form had no ability for cyanide adsorption, but calcination and acid treatment significantly improve its adsorptive properties. The best calcination conditions were determined to be at temperature of 600 degrees C and calcination time of 1h. The scanning electron microscope (SEM), wavelength-dispersive X-ray (WDX), X-ray fluorescence (XRF), and X-ray diffraction (XRD) analysis methods were used to explain the adsorptive properties of the adsorbents. The loading capacity of metakaolin increased from 0.66 to 5.32mg/g, and the loading capacity of acid-treated metakaolin increased from 1.33 to 10.67mg/g by increasing the initial cyanide concentration from 25 to 531mg/L. The kinetics of cyanide adsorption onto both adsorbents increases by increasing the initial cyanide concentration (25-531mg/L) and solution temperature (30-50 degrees C). The equilibrium and kinetic data on both adsorbents are best fitted by the Freundlich isotherm and pseudo-second-order kinetic models, respectively. The thermodynamic study showed that the cyanide adsorption onto both adsorbents is endothermic and spontaneous in nature. The activation energy for the cyanide adsorption onto metakaolin and acid-treated metakaolin was determined to be 16.68 and 5.79kJ/mol which indicates that the adsorption of cyanide ions onto metakaolin is chemisorption and onto the acid-treated metakaolin is a physicochemical process.